UTS Science: Green energy

Feb 15

Facilitator: Professor, thank you so much for joining us today. First of all, tell usa little bit about the zinc oxide project.

Professor: The zinc oxide project is one where we're looking at improving the efficiencyof the light emission properties of that material. This follows on from work that we've previouslydone on material known as gallium nitride. That work started 10years ago and now hasgone completely through from having an idea about how to use this material as efficientlight-emitting material, all the way through now so it's a commercial product. This issomething that you'll see that's been implemented in a whole range of applications. It's sortof a silent revolution. The standard incandescent bulb that's been around for the past hundredyears will become a thing of the past in the next 10 years or so.

Facilitator: Okay, so just explain to me a little bit more about why it is so important. Professor: Well in terms of lighting, and this is known as solid-state lighting, sothis is a device known as a diode and a diode consists of a positive and negative or positiveand negative areas. With this material, because of these positive and negative areas, it setsup a little voltage barrier and this voltage barrier, if we apply a voltage to it, it canovercome the electrons, can overcome this barrier and that interaction will producelight. Now the advantage is it does this without producing any heat, so it's a very efficientprocess compared with, say, an incandescent bulb where 90 per cent of the energy that'sused is lost as heat rather than light. So it's a very low power for a very high brightness. Facilitator: So how, exactly, would this be used in people's everyday lives?

Professor: Well it's already, now, these light-emitting diode traffic lights have proliferated aroundthe city already. If you go to any traffic lights now you'll basically see that instead of one bulb it's actually comprised of something like 140 LEDs. Now the advantage with this,even though there's 140 of these, that because of their low power consumption that light assembly actually uses one-third less power than a conventional incandescent bulb. Even,for example, these torches or flashlights that we have here, you can see that the incandescentbulbs have been replaced with the LED devices here. The advantage here is this bulb lasts for 10years, so it has a very long lifetime and this is the same sort of technology thatwill be slowly introduced into domestic lighting. Actually lighting consumes something of theorder of 20 per cent of the total power worldwide. So if we can introduce solid-state lighting where we're actually using at least a half, you can see immediately that we have a 10per cent drop in our power usage which translates to a 10 per cent drop in the production of green house gases.

Facilitator: How does this apply with your research then?Professor: Well with our work, we work at a very fundamental level, understanding howwe can improve the efficiency of this material by growing this material with better quality. This material is all man made material, so it's grown atom by atom, layer by layer. Aspart of this process, this process is being continuously refined to make better and better quality materials and so we study the light emission from areas that are a millionth ofa millimetre to get a complete understanding of the mechanisms that are involved in producing the light emission. Facilitator: I imagine that means you have some pretty spectacular machinery.

Professor: Yes, like the one behind me here. This enables us to accelerate electrons tovery high speed and inject them into one of these materials, this new advanced materials,into this very small volume and then study how the light is emitted by the various attachments that are sitting on the microscope behind me. Facilitator: Okay, so let's put that in everyday terms. How long before we see results outside the lab?Professor: Well, as I said, in terms of the gallium nitride technology that we've beenworking on for 10 years, that's already there. That's out there. These are now engineering issues to make the product more cost efficient. What we're now working on is a material knownas zinc oxide. Zinc oxide has excellent properties, in some sense much better properties than gallium nitride and this is sort of the thrust of our research is trying to understand theoptical electrical properties of zinc oxide.

Facilitator: Can you give me a timeframe, a ballpark timeframe?Professor: Well we're not the only group working on this. There's a lot of groups around theworld that are working on this problem and as this technology improves and we can producemore efficient bulbs that use less power and emit more light and also as the scale of productionincreases, the cost of these will continue to fall. It's very possible that in the next,well certainly in the next 20 years, that there'll be no incandescent sources in useat all. Facilitator: Professor, thank you so much for your time and taking the time to explainsome very complex ideas. Professor: My pleasure. Facilitator: Best of luck with your research.

Professor: Thank you very much.

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